Okay, what's on the axes here?
>> So here we're looking at TCA, that's the contaminant they introduced here.
So the cumulative TCA is on the y axis and then we have elapsed time in days
as they're running this tank study on the x axis.
>> Actual milligrams coming out, sort of over time.
>> Exactly. >> And this is about a ten day study.
Trichloroethane is a pretty soluble component.
So they put DNAPL right there that interface and
how long will it take to dissolve all that DNAPL away?
>> In this case, within five days it had no DNAPL, no TCA DNAPL left.
And so, that's sort of your loaning period and
then your source's off then after that period.
>> I did a field visit to their lab, and they showed me the camera that actually
can measure how much of that DNAPL's still in there.
And that's the purple squares, right, they're going down.
So every day they're taking pictures of this with this x-ray camera.
I wanted them to do x-rays to see how my arteries were doing.
They said no, it's for DNAPL, we want to see how this works.
And after five days, all the DNAPL's gone,
and under the sort of a classic evection dispersions type simulation,
this thing should have cleaned up on, say, day six, right?
>> Yeah. >> But did it?
>> No, you're extending out here then into about ten days,right?
You see that cumulative mass discharge is still increasing after day five.
>> And then I'm looking at the actual green crosses on the bottom.
Is that on day six this is the mass itself.
In Low Permeability unit.
There's a 3000mg.
And then day seven, day nine.
>> So that's the mass that's been responsible then,
for keep you coming off there.
>> Yeah, so even just in five days of loading,
you had this material almost 4000mg.
4 grams of this TCA diffuse into this Low Permeability unit.
Okay, let's keep going on another classic field study.
This is from Chapman and Parker Water Resources Research 2005.
They got this field site in Connecticut, there's a source zone.
And it's flowing ground water sort of flowing under the building here.
And then we have Transect 1 as where they done a lot of measurements in here.
But a pretty amazing study, right?
>> Yeah, a classic study where you've got a lot of fuel data, a lot of modeling data
working together to sort of explain what's going on at this site.
>> Okay, so let's look at some of the field data.
What's going on here in terms of their course?
>> Well, this is a case on their left hand,
where you've got the distance from the interface.
So, 0 is basically the location of that interface,
where there's an aquifer on top an aquitard on the bottom.
And then you've got on the x-axis, the TCE concentration plotted in this case.
And so each one, under those individual points that's shown there,
is a concentration measurement from a soil sample that they got out of a core.
>> Now, I think it's milligrams per liter.
They're sort of doing some conversions, but
think about that as the concentration in the core space in that aquitard that silt.
And you can see on the right, where you got the sand above that red dashed line,
and you got this sort of silty clay underneath it, and
you have this mass in there.
And they did these calculations to say what's the mass balance, and they come up
with, you can see in this slide here, how much mass is underneath there.
>> Talking about 3,000 kilograms of TCE present
Just in that low-permeability zone that they were investigating.
>> And so at this site they completely isolated the denapple source.
The sort of denapple source out of circulation but
that plume is still being sustained at a lower level of course
by this 3000 kilograms, so pretty amazing, the sort of work in there.
Now at this site I think they also did some modeling work,
what's this graph show?
>> Again, we're talking concentration here of TCE,
that's basically being shown in these various monitoring wells over time.
And so time is there on the x axis, we see 1991 as the start.
1993, they installed an enclosure, right?
>> Right.
>> And then they waited to see what would happen then to
the concentration that they were observing in the monitoring roles.
It turns out you didn't see that drop to really low levels that you'd expect based
on that sort of dashed purplish blue line right there, what do they see instead?
>> So you got this tail line.
So the blue is what they were hoping to see once they isolated that source, and
concentrations did go down, but maybe one order of magnitude.
90% reduction in concentration, but it just didn't keep going down,
it started tailing out, and so with their modeling work they use
this to go into their computer modules they said that,
they think these matrixes and source might sustain this for hundreds of years.
>> Yeah. >> I think is what they came up with them.
So now let's wrapt it up for today and we'll talk about some of this lab and
field demonstrations, I think Key points here,
the matrix diffusion is important in many of our most common hydrogeologic settings.
>> Yeah, and again this isn't just something that's been determined
by modeling.
There's a lot of lab data,
a lot of field data sort of backed up that this is an important process.
>> Yeah, and some of the key sources out here,
the US Air Force, >> AFCAC did some great studies,
their Source Initiative papers from Colorado State and Colorado School mines.
And then this Chapman and Parker paper is a really good one.
And then more recently sort of project 1740, which you and
I were part of sort of tells the story of this matrix diffusion process.
